History can be boring, though, so if you stumbled upon this post after hours of frustrated research, you can skip straight to A Simple. However, I do encourage reading the full post to understand how these things work under the hood—you'll hopefully never have to Google line endings again!
To really understand the problem of CRLF vs. LF line endings, we need to brush up on a bit of typesetting history. People use letters, numbers, and symbols to communicate with one another.
It's how you're reading this post right now! But computers can only understand and work with numbers. Since the files on your computer consist of strings of human-readable characters, we need a system that allows us to convert back and forth between these two formats. The ASCII standard is that system—it maps characters like A and z to numbers, bridging the gap between human languages and the language of computers.
A certain subset are control characters , also known as non-printing characters. They aren't used to render visible characters; rather, they're used to perform unique actions, like deleting the previous character or inserting a newline. LF and CR are two such control characters, and they're both related to line endings in files. Their history dates back to the era of the typewriter, so we'll briefly look at how that works so you understand why we have two different control characters rather than just one.
Then, we'll look at how this affects the typical developer experience on a multi-OS codebase. Simply put, this character represents the end of a line of text. On Linux and Mac, this is equivalent to the start of a new line of text.
That distinction is important because Windows does not follow this convention. We'll discuss why once we learn about carriage returns. If you've ever seen a download progress bar on your terminal, this is how it works its magic!
By using the carriage return, your terminal can animate text in place by returning the cursor to the start of the current line and overwriting any previously rendered text.
That's cool, but you may be wondering where the need for such a character originated beyond just animating text, which happens to be a niche application. Back when dinosaurs roamed the earth, people used to lug around these chunky devices called typewriters. You feed the device a sheet of paper fastened to a mechanical roll known as the carriage.
With each keystroke, the typewriter prints letters using ink on your sheet of paper, shifting the carriage to the left to ensure that the next letter you type will appear to the right of the previous one. You can watch a typewriter being used in action to get a better sense for how this works. Of course, once you run out of space on the current line, you'll need to go down to the next line on your sheet of paper.
This is done by rotating the carriage to move the paper up a certain distance relative to the typewriter's "pen. In other words, you need some way to return the carriage to its starting position. And that's precisely the job of the carriage return : a metal lever attached to the left side of the carriage that, when pushed, returns the carriage to its starting position.
That's all good and well, but you're probably wondering how this is relevant in the world of computers, where carriages, levers, and all these contraptions seem obsolete. We're getting there! Moving on to the early 20th century, we arrive at the teletypewriter , yet another device predating the modern computer.
Basically, it works exactly the same way that a typewriter does, except instead of printing to a physical sheet of paper, it sends your message to a receiving party via a transmitter, either over a physical wire or radio waves.
Now we're digital! These devices needed to use both a line feed character LF and a carriage return character CR to allow you to type from the start of the next line of text.
That's exactly how the original typewriter worked, except it didn't have any notion of "characters" because it was a mechanically operated device.
With the teletype, this process is more or less automatic and triggered by a keystroke—you don't have to manually push some sort of "carriage" or move a sheet of paper up or down to achieve the same effect. It's easier to visualize this if you think of LF and CR as representing independent movements in either the horizontal or vertical direction, but not both. By itself, a line feed moves you down vertically; a carriage return resets your "cursor" to the very start of the current line.
We saw the physical analogue of CR and LF with typewriters—moving to the next line of text required rotating the carriage to move the sheet of paper up line feed , and returning your "cursor" to the start of that new line required using a mechanical piece aptly named the carriage return.
Microsoft has an excellent article explaining the history of CRLF in teletypes and early operating systems. Here's a relevant snippet:. This makes it seem like Windows is the odd one out when it's technically not. Developers usually get frustrated with line endings on Windows because CRLF is seen as an artifact of older times, when you actually needed both a carriage return and a line feed to represent newlines on devices like teletypes. It's easy to see why CRLF is redundant by today's standards—using both a carriage return and a line feed assumes that you're bound to the physical limitations of a typewriter, where you had to explicitly move your sheet of paper up and then reset the carriage to the left-hand margin.
AdrianMcCarthy It's a problem with the way close votes act as answers in a way; an answer claiming the two were the same could be downvoted and then greyed out as very, very wrong, but it only takes 4 agreeing votes comparable to upvotes to have a very wrong close happen, with no way to counter the vote until after it's happened. This formulation of the question is admittedly better, but it is still for all practical purposes the same question.
Korpela: No, it really isn't. Show 2 more comments. Active Oldest Votes. Stevoisiak Would it be accurate, then, to say that a text file created on Windows is the most compatible of the three i. Hashim it might display properly but trying to run a textual shell script with carriage returns will usually result in an error — Omer Tuchfeld. With as often as they are used, that actually translates to a huge amount of data. Show 1 more comment. Yves M. Taylor Leese Taylor Leese The "vertical tab"-character moves the cursor down and keep the position in the line, not the LF-character.
Add a comment. Peter Peter k 49 49 gold badges silver badges bronze badges. In addition, Wikipedia:Newline. That was what returned the carriage on typewriters.
So, mostly correct. The superior LFCR option is sadly missing. Flimm yes, backslash is the commonly designated character to "escape" what follows it. Manu Manu Even today we can still see this mechanical logic in any inktjet-printer I love to understand since I hate to learn.
My other memory-tricks are: "mac? That's not what it says. Adrian Will you take persona experience? Adrian 2 Don't forget, this was in the electro-mechanical era, where each character did exactly one function.
Five data bits, between one start bit and one-and-a-half stop bits. How can you have half a bit? By waiting half a bit time before starting to send the next character, to give the print head time to return to center. Show 5 more comments. Adrian McCarthy Unix adopted plain LF as the line termination sequence. If you get this setting wrong, you get stairstep text, where. The implicit CR before LF is a unix invention, probably as an economy, since it saves one byte per line. Comments are closed.
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